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针对中功率蓝光及相应的白光LED器件进行加速老化实验,并具体分析了器件中硅胶和绿红混合荧光粉等封装材料对老化行为的影响和失效机理。在测试器件的光电老化行为之后,利用反射光谱和飞行时间二次离子质谱对失效器件进行了结构分析。结果表明,温度和湿度对蓝光和白光器件老化行为具有不同的影响。对于中功率蓝光LED而言,其光衰的主要原因是由于S、Cl等元素的引入及氧化等因素引起的黄化导致了透明硅胶反射率的下降。而对于绿红混合荧光粉组成的中功率白光LED来说,其光衰和色漂问题主要归结于在高温特别是高湿环境下工作,器件中荧光粉和硅胶等封装材料发生了一些化学反应,使荧光粉发生分解,并引起了荧光转换效率的下降。
Accelerated aging experiments were carried out for the middle-power blue light and the corresponding white LED devices. The effects of the encapsulation materials such as silica gel, green-red mixed phosphor and the like on the aging behavior and the failure mechanism were analyzed in detail. After the photoelectrical aging behavior of the device was tested, the failure device was structurally analyzed by reflectance spectroscopy and time of flight secondary ion mass spectrometry. The results show that temperature and humidity have different effects on the aging behavior of blue and white devices. For medium power blue LED, the main reason of its light failure is due to the introduction of S, Cl and other elements caused by oxidation and other factors led to the decline of the transparency of the silica gel. However, for the middle-power white LEDs composed of green-red phosphors, the light fades and bleaching problems are mainly due to the high temperature and especially the high humidity environment. Some chemical reactions occur in the packaging materials such as phosphor and silica gel , Causes the phosphor to decompose, and causes the fluorescence conversion efficiency to drop.